Update docs for v1.5.3
diff --git a/docs/dyn/servicemanagement_v1.services.html b/docs/dyn/servicemanagement_v1.services.html
index 6cf48e8..f5c29d0 100644
--- a/docs/dyn/servicemanagement_v1.services.html
+++ b/docs/dyn/servicemanagement_v1.services.html
@@ -476,6 +476,9 @@
 
 Operation<response: EnableServiceResponse>
 
+google.rpc.Status errors may contain a
+google.rpc.PreconditionFailure error detail.
+
 Args:
   serviceName: string, Name of the service to enable. Specifying an unknown service name will
 cause the request to fail. (required)
@@ -778,7 +781,9 @@
           },
         ],
         "displayName": "A String", # Optional. A concise name for the monitored resource type that might be
-            # displayed in user interfaces. For example, `"Google Cloud SQL Database"`.
+            # displayed in user interfaces. It should be a Title Cased Noun Phrase,
+            # without any article or other determiners. For example,
+            # `"Google Cloud SQL Database"`.
         "description": "A String", # Optional. A detailed description of the monitored resource type that might
             # be used in documentation.
         "name": "A String", # Optional. The resource name of the monitored resource descriptor:
@@ -1037,8 +1042,13 @@
                   #                bookstore_web.apps.googleusercontent.com
             },
           ],
-          "allowWithoutCredential": True or False, # Whether to allow requests without a credential.  If quota is enabled, an
-              # API key is required for such request to pass the quota check.
+          "allowWithoutCredential": True or False, # Whether to allow requests without a credential. The credential can be
+              # an OAuth token, Google cookies (first-party auth) or EndUserCreds.
+              #
+              # For requests without credentials, if the service control environment is
+              # specified, each incoming request **must** be associated with a service
+              # consumer. This can be done by passing an API key that belongs to a consumer
+              # project.
           "selector": "A String", # Selects the methods to which this rule applies.
               #
               # Refer to selector for syntax details.